I found this thread at FSB, but it's a little unclear on if this would work. Thoughts?
http://freestompboxes.org/viewtopic.php?f=10&t=16837&hilit=a%2Fb%2Fy+mute (http://freestompboxes.org/viewtopic.php?f=10&t=16837&hilit=a%2Fb%2Fy+mute)
To note, I don't see why it wouldn't. Just go from the input jack to the Input lug of the Tuner switch, the the output of the tuner switch goes to the Input of whatever circuit I throw in there.
If I didn't want the tuner mute, but literally just wanted a master bypass switch, I could just ground that lug marked "tuner", right?